Gas chromatography uses a flow controller to control the flow rate of gas such as carrier gas. A flow controller for gas chromatography is generally configured such that pressure control valves, pressure sensors, and pipes are connected to a channel assembly comprised of a plurality of metal plates laminated and having channels inside thereof (see Patent Document 1). When controlling the flow rate of gas using a pressure sensor, the flow rate of gas is controlled by connecting a resistance pipe to a downstream side of a channel assembly, adjusting the channel resistance of a channel where the gas flows to a certain channel resistance value, and exerting feedback control on a pressure control valve to control the degree of opening based on a pressure value detected by the pressure sensor.
Examples of a detector for gas chromatography include a flame ionization detector (FID), a thermal conductivity detector (TCD), a flame photometric detector (FPD), and a flame thermionic detector (FTD). Kinds and the number of gasses, the flow rate of which need to be controlled, differ depending on the types of the detectors, and the channel resistance needed for the flow controller differs depending on the types of the detectors. Different types of detectors therefore need respective flow controllers; however, a dedicated flow controller for each type of detector increases the cost. Thus, the flow controller suitable for each detector is configured by changing types of a resistance pipe to achieve a certain relationship between the pressure and the flow rate depending on the type of the detector, while employing the same basic configuration of the flow controller.
PATENT DOCUMENT 1: Japanese Unexamined Patent Publication No. 2005-156214